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Re: [CQ-Contest] SO2R Technical Question - Round III - Antennas

To: "CQcontest Reflector" <cq-contest@contesting.com>
Subject: Re: [CQ-Contest] SO2R Technical Question - Round III - Antennas
From: "Tom Rauch" <w8ji@contesting.com>
Reply-to: Tom Rauch <w8ji@contesting.com>
Date: Thu, 24 Jan 2008 18:05:01 -0500
List-post: <mailto:cq-contest@contesting.com>
> Antennas.  I think I have an issue with antennas because 
> of make up of my location.  I have a 60 foot tower with a 
> C3E - 80 and 40 meter inverted -V dipoles on separate 
> feedlines but at the same height on the tower, a 160 meter 
> Inverted-L on the tower...and a full size quarter-wave 
> vertical in the yard with 32 radials.  I was planning on 
> changing out the vertical for a Butternut 6 band model or 
> something similar, but as I was looking at the 
> installation the antenna would be very close to both the 
> 160 -80- and 40 meter antennas....less than 15 feet.  I am 
> on an 80 by 150 foot lot.  (I think SO2R is gonna get 
> expensive when I tell the YL we have to move!)  So, is it 
> worthwhile to even consider doing SO2R on such a small lot 
> because of the proximity of the antennas.  This is a 
> considerable investment....minus the new farmstead.

Lee,

While it is more difficult I don't thing it is impossible. 
We have no problems at all without using any filters even 
using antennas on the same tower:
http://www.w8ji.com/rotating_tower_w8ji.htm

I'd sure do some tests first though to avoid trashing a 
radio. You can test with something as simple as a small 
light bulb, like a miniature 12V lamp. If a 50mA 12V bulb 
lights enough to see it get red on the filament when you 
excite another antenna, you better add a receiver filter 
(assuming you are working a different band) on that antenna!

Your mileage will vary with a vertical but the Butternut, 
Hytower, or Hustler BTV series are good choices.  The 
biggest headache with verticals is ground clutter and poor 
ground systems. Of course there are very bad antennas like 
the Gap or Sommer T25 that are virtual dummy loads.

If you look at that big stack of Yagis I have for 40m, a 
25ft tall DXE vertical over 40-50 radials works about 95% of 
what the stack does. It's typically about 10dB-15dB weaker. 
That's actually plenty good for a second antenna that is 
just for going around knocking off mults.

I'm always amazed at what a small antenna, like a dipole at 
50-60 feet on 160 meters, can work. it might not clear a big 
swath and hold a frequency, but when people listen and you 
call them you certainly don't need to be the biggest guy on 
the block.

I am just getting into this for higher bands so I'm learning 
about the optimum hardware for setups like you are planning, 
although I have put some work into two radios on 160 for 
several years and I sometimes work two bands at the same 
time in normal operation.

73 Tom










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